The semiconductor device represented by a silicon semiconductor is highly integrated, and the minimum dimension of a circuit pattern (design rule) in the memory device and logic device is thinned, in order to meet the needs of the market for higher speed and miniaturized scale in its performances. In order to satisfy the demand for fine semiconductor devices, there has been employed a technique for flattening a device surface, such as a CMP method in which the device surface is polished using fine particles of silicon oxide, aluminum oxide, serium oxide, or the like.
For instance, in order to satisfy a multi-layered structure of a circuit pattern, there is a metal CMP method represented by damascene method in which a groove is provided in an interlayer insulation film formed between an upper layer circuit and a lower layer circuit, and a line metal (copper, aluminum, tungsten or the like) is filled into the grooves, and thereafter an excessive metal film is polished.
However, in these steps using CMP method (hereinafter CMP step), there are generated deposition and residues of polishing particles and device-derived inorganic fine particles, and further metal impurities such as iron, copper, aluminum and tungsten derived from a line material on a device, so that these deposited residues cause lattice defects of a substrate, or troubles such as insulation failure and lamination defects of an oxidized film, or breakage of line, or short-circuiting or leakage due to the fine particles entering between the lines, whereby causing quality failure and lowering in production yield. Therefore, a cleaning process is essential.
The tendency described above is more strongly exhibited when the integration degree of the semiconductor device increases and the circuit pattern becomes finer. Therefore, in order to suppress quality worsening or lowering in yield of a manufactured article caused by the finer formation of the circuit patterns, RCA cleaning process has been most widely used as a cleaning process. The RCA cleaning process is roughly divided into two steps depending upon the objects to be removed: The removal of fine particles includes a process using ammonia and an aqueous hydrogen peroxide (SC-1 process); and the removal of metal impurities includes a process using hydrochloric acid and an aqueous hydrogen peroxide (SC-2 process). A cleaning process such as ultrasonic wave (megasonic) in mega-Hertz region, with cleaning with a diluted aqueous hydrofluoric acid, or brush-scrub is also carried out between each of the steps.
However, there arise some problems in the cleaning with hydrofluoric acid used in each step such that since the corrosion to a line metal (copper, tungsten or the like) or the like is large, the film thickness and the line thickness fluctuate, so that a pattern shape of a designed size cannot be obtained, whereby causing wrong influences to properties and qualities such electric properties of the semiconductor device with advanced fineness and thinning. In addition, recently, the fine particles to be removed have become very fine, thereby resulting in difficulty in the removal of the fine particles. Furthermore, the required level of the removal of the metal impurities has become high, so that its required level cannot be satisfactorily met by the above-mentioned RCA cleaning process.
Also, in order to meet the problem of corrosion of line mentioned above and improve the required level of the removal of the metal impurities, a detergent using an organic acid such as oxalic acid or citric acid has been newly developed. However, the above-mentioned problems have not yet been solved thereby.
Further, Japanese Patent Laid-Open No. Hei 11-251280 reports a detergent using a reducing agent and an acid. However, this detergent has a pH of less than 3.0, so that the line metal (especially copper) is corroded. Likewise, the above-mentioned problems have not yet been solved thereby.